Rabbits received classical conditioning of the nictitating membrane response (NMR) in a trace conditioning paradigm. In this paradigm, a 250-ms tone conditioned stimulus (CS) occurs, after which there is a 500-ms period of time in which no stimuli occur (the trace interval), followed by a 100-ms air puff unconditioned stimulus (UCS). In Experiment 1, lesions of the hippocampus or cingulate/retrosplenial cortex disrupted acquisition of the long-latency or adaptive conditioned response relative to unoperated controls and animals that received neocortical lesions that spared the cingulate/retrosplenial areas. When animals with hippocampal or cingulate/retrosplenial lesions were switched to a standard delay paradigm in which the CS and UCS were contiguous in time, they acquired in about the same number of trials as naive rabbits. In a second experiment multiple-unit activity in area CA1 of the hippocampus was examined during acquisition of the trace conditioned response (CR). Three groups of animals were tested: animals that had a 500-ms trace interval (Group T-500), animals that received explicitly unpaired presentations of the CS and UCS (Group UP), and animals that underwent conditioning with a 2,000-ms trace interval (Group T-2000). Animals in Group T-500 acquired the CR in about 500 trials. Early in training, and well before any CRs occurred, there was a substantial increase in neuronal activity in the hippocampus that began during the CS and persisted through the trace interval. There was also an increase in the UCS period that modeled the amplitude-time course of the behavioral unconditioned response. Later in conditioning as CRs emerged, there was no longer neuronal bursting throughout the CS + trace period. Rather, the activity shifted to later in the trace interval and formed a model of the amplitude-time course of the behavioral CR. Activity during the UCS period was similar to that seen earlier in conditioning. Animals in Group UP showed no behavioral conditioning and no increase in neuronal activity. Animals in Group T-2000 showed no long-latency behavioral conditioning and no increase in neuronal activity. The data are discussed in terms of the role of the hippocampus in conditioning during situations in which the CS and UCS are not contiguous in time.

Galantamine 16 and 24 mg/day significantly benefits the cognitive, functional, and behavioral symptoms of AD as compared with placebo. Slow dose escalation appears to enhance the tolerability of galantamine, minimizing the incidence and severity of adverse events.

No abstract

The 7 Minute Screen appears highly sensitive to AD and may be useful in helping to make initial distinctions between patients experiencing cognitive changes related to the normal aging process and those experiencing cognitive deficits related to dementing disorders such as AD. It has reasonable interrater and test-retest reliability, can be administered in a brief period, and requires no clinical judgment and minimal training.

No abstract

Bilateral aspiration of the dorsal hippocampus produced a disruption of blocking of the rabbit's nictitating membrane response in Kamin's two-stage paradigm (Experiment 1), but had no effect on the formation of a Pavlovian conditioned inhibitor, (Experiment 2).

Hippocampal ablation has no effect on the acquisition of the rabbit's classically conditioned nictitating membrane response. Systemic administration of scopolamine, which alters hippocampal neuronal activity, severely retards acquisition of the conditioned response in normal animals and those with cortical ablations. In animals with hippocampal ablations, however, scopolamine has no effect on conditioning. These findings suggest that altered neuronal activity in the hippocampus is more detrimental to conditioning than removing the structure.

Human subjects ranging in age from 18 to 85 years underwent classical conditioning of the eyeblink response to a tone conditioned stimulus (CS) and an air-puff unconditioned stimulus (UCS). There was a decline in percentage of conditioned responses with age. This decline was most noticeable in subjects over age 50. These conditioning deficits were not due to age-related changes in sensitivity to the tone CS or the air-puff UCS, nor could the conditioning deficits be attributed to an age-related decline in general cognitive abilities or to changes in spontaneous blink rates. The results are discussed in terms of using the classically conditioned eyeblink in humans in conjunction with the classically conditioned nictitating membrane response in rabbits as a model system for studying the neurobiology of age-related conditioning deficits.